RENNtech is proud to announce our latest ECU performance upgrade for the all new M278 engine currently in the C218 CLS 550, E550, CL550, S550 and other upcoming Mercedes models. We have been hard at work refining our performance tune for these engines and are pleased to announce our latest ECU upgrade. Itís clear that the 4.6L V8 biturbo engine from Mercedes is certainly underrated from the factory and though our extensive testing and R&D; our ECU upgrade truly unleashes the performance lurking in the M278 engine.

RENNtechís ECU upgrade for the M278 offers huge gains across the entire RPM range; increasing crank performance numbers an additional 70 HP and 80 TQ. This translates to an astonishing 530 HP and 606 lb/ft of torque at the crank! These numbers are factored at a conservative 15% drive train loss.

The performance increase is instantly noticeable at the bottom end and continues throughout the biturbo engines broad powerband.

Here is the CLS 550 (C218) dyno sheet:

Our CLS 550 stage 1 ECU upgrade is available now for $2,740. For additional information, visit out product webpage:

By the way, the guy who installed the RENNtech tune (post #40 above) got interested in the tune after I posted the RT press release at another site. I learned about it on this site: so chalk one sale from Benzboost (and me).

Before I choose a tuner for my CLS550 4Matic, I'd like to be educated as best as possible. I wish there was more info/feedback from RENNtech within this thread... as well as current uses with the M278 tune. I've tried calling and emailing RENNtech directly, but they seem elusive and/or unwilling to answer some simple questions. Since I don't race, I'm only interested in everyday street characteristics. Is it too much to ask, "What should I expect with my purchase?"

Sticky- Perhaps you can find out the following:
a) Is the street drive-ability compromised in any way?
b) What about the slight turbo lag I often experience at light throttle... can that be eliminated?
c) Are the transmission shift points altered in either the economy or sport mode?
d) Is the speed governor eliminated (not that I will ever test that feature)?
e) How is the fuel economy impacted?
f) Have free flow air cleaners been tested with this tune... do they recommend them?
g) Why do they list all the M278 engines with the same power when the factory rated them differently?
h) Are more tune updates in the works... what about vehicle accessories?

Anything else they could mention for features would be appreciated... I'm just trying to learn exactly what to expect.

427
Here's the response to some of your questions from the owner of the '12 E550C with the RENNtech tune.
The others would be RENNtech's to answer.

a) The most noticable change was the throttle tip in, seems more immediate and almost exaggerated in sport mode in normal mode it as you might expect. But to answer directly the change, to this point hasn't negatively impacted day to day driving. Except to say maybe a bit more fun.
b) As to turbo lag, it's probablly as responsive as possible and still have a turbo. I am suspect of someone that tells me they have a performance turbo and has "no" lag. Lag is part and parcel to the turbo.
c) I don't believe the shift points have been altered, could be wrong but don't think so.
d) Also believe the speed governor/rev-limiter are still intact, as they would tie directly to warante implications.
e) As many have stated, the mileage might be a bit better but dip into the throttle a bit more so it's probablly a wash. But certainly no losses.

Before I choose a tuner for my CLS550 4Matic, I'd like to be educated as best as possible. I wish there was more info/feedback from RENNtech within this thread... as well as current uses with the M278 tune. I've tried calling and emailing RENNtech directly, but they seem elusive and/or unwilling to answer some simple questions. Since I don't race, I'm only interested in everyday street characteristics. Is it too much to ask, "What should I expect with my purchase?"

Sticky- Perhaps you can find out the following:
a) Is the street drive-ability compromised in any way?
b) What about the slight turbo lag I often experience at light throttle... can that be eliminated?
c) Are the transmission shift points altered in either the economy or sport mode?
d) Is the speed governor eliminated (not that I will ever test that feature)?
e) How is the fuel economy impacted?
f) Have free flow air cleaners been tested with this tune... do they recommend them?
g) Why do they list all the M278 engines with the same power when the factory rated them differently?
h) Are more tune updates in the works... what about vehicle accessories?

Anything else they could mention for features would be appreciated... I'm just trying to learn exactly what to expect.

Thanx,
427

A lot of these were answered but let me answer what I know. Also, paging @m54b25

a. no, it should be better with increased torque.
b. that is likely a function of having a turbocharged motor but throttle response can be changed.
c. don't think so
d. yes
e. heavier foot, it will go down.
f. freer flowing filter will only help.
g. just likely to save time and a small oversight.
h. yes, more tune updates in the works and accessories.

Sticky points are well noted. The M278 4.7L V8 Biturbo with a tune will actually perform better all around with the increase torque. Usually customers with heavier 4matics such as S, ML & CL class will be notice a great initial drive dynamics acceleration increase from stock. It will be comparable in performance acceleration of similar AMG63 class w/o PP biturbo cars. Some other points:

1) Fuel economy will remain same if you can drive the same way after the tune.
2) Speed limiter can be raised upon customer request
3) Transmission adaptation shift points remains same in Comfort or Sport mode.
4) Tune are available with optional high flow kat downpipes, and/or modified ECO mode stop start at no additional charge.

Originally Posted by Sticky

A lot of these were answered but let me answer what I know. Also, paging @m54b25

a. no, it should be better with increased torque.
b. that is likely a function of having a turbocharged motor but throttle response can be changed.
c. don't think so
d. yes
e. heavier foot, it will go down.
f. freer flowing filter will only help.
g. just likely to save time and a small oversight.
h. yes, more tune updates in the works and accessories.

Sticky points are well noted. The M278 4.7L V8 Biturbo with a tune will actually perform better all around with the increase torque. Usually customers with heavier 4matics such as S, ML & CL class will be notice a great initial drive dynamics acceleration increase from stock. It will be comparable in performance acceleration of similar AMG63 class w/o PP biturbo cars. Some other points:

1) Fuel economy will remain same if you can drive the same way after the tune.
2) Speed limiter can be raised upon customer request
3) Transmission adaptation shift points remains same in Comfort or Sport mode.
4) Tune are available with optional high flow kat downpipes, and/or modified ECO mode stop start at no additional charge.

a. no, it should be better with increased torque.
b. that is likely a function of having a turbocharged motor but throttle response can be changed.
c. don't think so
d. yes
e. heavier foot, it will go down.
f. freer flowing filter will only help.
g. just likely to save time and a small oversight.
h. yes, more tune updates in the works and accessories.

Sticky - I appreciate your response and assistance in reaching out to RENNtech... this is all very helpful.

Sticky points are well noted. The M278 4.7L V8 Biturbo with a tune will actually perform better all around with the increase torque. Usually customers with heavier 4matics such as S, ML & CL class will be notice a great initial drive dynamics acceleration increase from stock. It will be comparable in performance acceleration of similar AMG63 class w/o PP biturbo cars. Some other points:

1) Fuel economy will remain same if you can drive the same way after the tune.
2) Speed limiter can be raised upon customer request
3) Transmission adaptation shift points remains same in Comfort or Sport mode.
4) Tune are available with optional high flow kat downpipes, and/or modified ECO mode stop start at no additional charge.

I would only be speculating, you have to ask @m54b25 for something concrete.

Thanx, Sticky. I'll be giving RENNtech another call shortly, but I want to run a base dyno first. If all goes well, I should have some free time at the end of the month and hope to get that accomplished.

Thanx, Sticky. I'll be giving RENNtech another call shortly, but I want to run a base dyno first. If all goes well, I should have some free time at the end of the month and hope to get that accomplished.